Gel Polymer Electrolyte for Lithium Battery Safety

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Solution Overview

Problem

Lithium secondary batteries face challenges with liquid electrolyte solutions due to high volatility, low safety, and instability at high voltages, leading to reduced capacity and increased risk of thermal runaway, while gel polymer electrolytes have lower ionic conductivity and inadequate flame retardancy.

Innovation Solution

A gel polymer electrolyte composition for lithium secondary batteries is developed, incorporating a lithium salt, non-aqueous organic solvent, ionic liquid, oligomer, and flame retardant, which improves high-temperature stability and flame retardancy by enhancing ionic conductivity and oxidation resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If liquid electrolyte solution is used to increase energy density and driving voltage, then battery capacity and operating potential are improved, but safety deteriorates due to high volatility and combustion risk

Engineering Contradiction:

Improveenergy densityVSAvoidcombustion risk

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent changes the physical state of the electrolyte from liquid to gel polymer form, fundamentally altering the volatility and combustion characteristics while maintaining ionic conductivity for energy storage function

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite gel polymer electrolyte combining polymer matrix with ionic liquid and flame retardant additives, achieving both high ionic conductivity for energy density and flame retardancy for safety

Inventive Principle:

Principle #40Composite materials

2Power

If liquid electrolyte solution is used at high voltage (4.3 V or more), then driving voltage and energy density are improved, but stability deteriorates due to oxidative decomposition

Engineering Contradiction:

Improvedriving voltageVSAvoidelectrolyte stability

Core Design Contradiction:

PowerVSStability of the object's composition

Solution Approach 1:

The patent changes the chemical composition and physical state of the electrolyte to gel polymer form, which inherently provides better oxidation resistance at high voltages compared to liquid electrolytes

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent incorporates flame retardant additives that form protective films on electrode surfaces, sacrificing the additives to prevent decomposition of the main electrolyte composition at high voltages

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Object-affected harmful factors

If gel polymer electrolyte is used to improve safety and reduce volatility, then flame retardancy is improved, but ionic conductivity deteriorates

Engineering Contradiction:

Improveflame retardancyVSAvoidionic conductivity

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent creates a composite gel polymer electrolyte combining polymer matrix with ionic liquid components that provide high ionic conductivity, while incorporating flame retardant additives to ensure safety, achieving both improved conductivity and flame retardancy

Inventive Principle:

Principle #40Composite materials

4Reliability

If carbonate-based organic solvent is used in gel polymer electrolyte, then ionic conductivity is improved, but flame retardancy deteriorates

Engineering Contradiction:

Improveionic conductivityVSAvoidflame retardancy

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces flame retardant additives as intermediary substances that form protective barriers between the carbonate-based solvent and oxygen, preventing combustion while allowing ionic conductivity to be maintained through the solvent system

Inventive Principle:

Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The composition achieves improved flame retardancy and high-temperature stability, reducing the risk of thermal runaway and maintaining capacity, while ensuring safe operation at high voltages.

Implementation Method 1

incorporating a lithium salt, non-aqueous organic solvent, ionic liquid, oligomer, and flame retardant, which improves high-temperature stability and flame retardancy by enhancing ionic conductivity and oxidation resistance

Methodology Applied

Scientific EffectIonic conductivity enhancement: Conduction (electrical)

Implementation Method 2

The composition achieves improved flame retardancy and high-temperature stability, reducing the risk of thermal runaway and maintaining capacity, while ensuring safe operation at high voltages

Methodology Applied

Scientific EffectFlame retardancy: Combustion

Data Source

PatentEP3648230B1Gel polymer electrolyte composition and lithium secondary battery including the same

Publication Date: 2022.08.10 LG ENERGY SOLUTION LTD

AI summary

The present invention relates to a gel polymer electrolyte composition for a lithium secondary battery, a gel polymer electrolyte prepared by polymerizing the same, and a secondary battery including the gel polymer electrolyte, and particularly, to a gel polymer electrolyte composition for a lithium secondary battery, which includes a lithium salt, a non-aqueous organic solvent, an ionic liquid, an oligomer having a specific structure, a flame retardant, and a polymerization initiator, a gel polymer electrolyte formed by polymerizing the gel polymer electrolyte composition in an inert atmosphere, and a lithium secondary battery in which flame retardancy and high-temperature stability are improved by including the gel polymer electrolyte.